Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/73—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals characterised by the process
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
  • C23C22/08—Orthophosphates

Definitions

• the present invention relates to a method for chemical treament of the surface of an iron substrate. More particularly, it relates to an industrially advantageous method for chemical treatment of the surface of an iron substrate in fewer steps with the omission of water rinsing.
• the chemical treatment of the surface of an iron substrate has been usually carried out in the following order: (1) pretreatment (acid cleaning), (2) water rinsing, (3) after treatment (neutralizing), (4) water rinsing and (5) drying.
• a paint composition is ordinarily applied on the resulting surface.
• the treatment of the surface of a large iron structure, such as the hull of ship or a block of bridge, according to such conventional method meets various problems. For instance, the quick transference of the structure, the rapid elimination of the treating solution attached and remained on the surface and the prompt drying of the wet surface are necessary.
• the omission of the water rinsing step has been highly desired.
• the water rinsing between the pretreatment and the after treatment (which is hereinafter referred to as "intermediary water rinsing") is omitted, the treating solution in the after treatment is considerably contaminated with the treating solution of the pretreatment, whereby the effects of the former, such as neutralization, rust prevention and surface conditioning of the surface for painting, are decreased.
• final water rinsing results in part of the treating solution remaining in the after treatment and/or the treating solution in the pretreatment being contaminated therein, whereby the corrosion resistance and the adhesiveness of the coating film formed by the application of a paint composition thereto may be unfavorably deteriorated.
• the modifications of the treating solutions in the pretreatment and the after treatment become necessary.
• a basic object of the present invention is to provide a method for the chemical treatment of the surface of an iron substrate, particularly of a large iron structure, in fewer steps without producing any defects.
• Another object of this invention is to provide a method for chemical treatment of the surface of an iron substrate, particularly of a large iron structure, without any water rinsing step.
• a further object of the invention is to provide treating solutions to be used respectively in the pretreatment step and the after treatment step, which makes it possible to omit the water rinsing steps.
• a method for chemical treatment of the surface of an iron substrate which comprises (a) treating the surface with an aqueous solution containing phosphoric acid in a concentration of 0.5 to 80 weight/volume percent, (b) subjecting the surface without water rinsing to treatment with an aqueous solution containing phosphoric acid with a substance capable of reacting with the phosphoric acid to give a water-soluble salt, which is hydrolyzed or reacted with the iron substrate to form a volatile base (which is hereinafter referred to as "substance (A)”), and/or a substance capable of reacting with the phosphoric acid to give a water-soluble salt, which is hydrolyzed or reacted with the iron substrate to form a non-volatile base (which is hereinafter referred to as "substance (B)”), the pH of the aqueous solution being pH 1 to 9, the total ion concentration being 0.2 to 8 weight/volume %, and the concentration of the cation forming
• pretreatment solution an aqueous solution containing phosphoric acid in a concentration of 0.5 to 80 weight/volume % (which is hereinafter referred to as "pretreatment solution").
• the pretreatment solution is necessary for removal of rusts on the surface to be treated and prevention of rusting until the treatment in the step (b) is made.
• hydrochloric acid, sulfuric acid, sulfamic acid and the like there have been also employed.
• phosphoric acid only phosphoric acid is used, because it is capable of forming a rust proof layer of iron phosphate on the surface of the iron substrate and, even when contaminated into the treating solution in the step (b), can be reacted with the substance (A) to form a useful substance.
• the phosphoric acid there may be employed not only orthophosphoric acid but also any condensed phosphoric acid such as pyrophosphoric acid or tripolyphosphoric acid.
• the term "phosphoric acid” herein used is intended to mean the one wherein the H 2 O/P 2 O 5 ratio is larger than 0 and not more than 3.
• the concentration of the phosphoric acid in the pretreatment solution may be appropriately decided, depending on the amount of the rusts to be removed and is usually from 0.5 to 80 weight/volume percent, preferably from 7 to 30 weight/volume percent. In case the concentration is less than 0.5 weight/volume percent, a large amount of precipitates is unfavorably formed in the pretreatment solution. In case of the concentration is more than 80 weight/volume percent, the "drag out" of the phosphoric acid into the treating solution in the step (b) becomes too much, and it is uneconomical.
• the pretreatment solution preferably contains an acid pickling inhibitor in addition to phosphoric acid.
• the acid pickling inhibitor functions not only for preventing the excessive dissolution of the iron substrate and the waste consumption of the phosphoric acid, but also for preventing the formation of a white powdery layer of iron phosphate resulting from the excessive reaction between the iron substrate and the phosphoric acid remaining on the surface when the iron substrate after the treatment in the step (a) is allowed to stand for a long period of time without subjecting to the subsequent treatment in the step (b).
• the acid pickling inhibitor include any conventional one such as an organic one (e.g.
• stannous compounds e.g. arsenic compounds
• One or more of these acid pickling inhibitors may be employed in a concentration of 0.001 to 1 weight/volume percent which can realize at least a 50 percent inhibitory efficiency of the acid pickling. When the inhibitory efficiency is less than 50 %, the preventive effect of forming said white powdery layer is insufficient.
• a thick adsorptive layer of the acid pickling inhibitor is formed on the surface of the iron substrate so that the reaction of the treating solution in the subsequent step (b) with the iron substrate is prevented and the corrosion resistance and the adhesiveness of the coating film formed later with a paint composition may be reduced.
• step (b) there is used an aqueous solution containing phosphoric acid with the substance (A) and/or the substance (B) as the essential components (which is hereinafter referred to as "after treatment solution").
• the phosphoric acid to be used for the step (b) may be the substantially same one as for the step (a).
• the term "phosphoric acid” may be construed to mean one wherein the H 2 O/P 2 O 5 ratio is larger than 0 and not more than 3.
• the phosphoric acid in the step (b) is not necessarily required to be used in the form of a free acid and may be used in the form of a salt with the substance (A) and/or, if used, the substance (B). When the phosphoric acid is used in such salt form, the use of the substance (A) and/or the substance (B) may be omitted.
• the substance (A) is one which can react with phosphoric acid to give a water-soluble salt, which is then hydrolyzed and/or reacted with the iron substrate to form a volatile base.
• Specific examples of the substance (A) are ammonia, ammonium hydroxide, hydroxylamine, tetraalkylammonium hydroxide of which the alkyl group has not more than 2 carbon atoms (e.g. tetramethylammonium hydroxide, tetraethylammonium hydroxide), alkylamine of which the alkyl group has not more than 2 carbon atoms (e.g.
• phosphate of the substance (A) are ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, etc.
• the substance (B) is to be the one which can react with phosphoric acid to give a water-soluble salt, which is then hydrolyzed and/or reacted with the iron substrate to form a non-volatile base is formed.
• the subtance (B) are alkali metal (e.g. potassium, sodium), alkali metal oxide (e.g. sodium oxide, potassium oxide, sodium peroxide), alkali metal hydroxide (e.g. sodium hydroxide, potassium hydroxide), etc.
• Specific examples of the phosphate of the substance (B) are sodium phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium metaphosphate, sodium pyrophosphate, etc.
• substance (A) and/or the substance (B) there may be used a substance which has both the properties required for (A) and (B).
• Specific examples of such substance are ammonium sodium hydrogen phosphate, ammonium potassium hydrogen phosphate, etc.
• the total ion concentration in the after treatment solution is to be from 0.2 to 8 weight/volume percent, preferably from 0.2 to 5 weight/volume percent.
• concentration is less than 0.2 weight/volume percent, a sufficient rust proof effect is not obtained.
• concentration is over 8 weight/volume percent, the amount of the electrolyte remaining on the surface of the iron substrate is much increased irrespective of the kind of the electrolyte and deteriorates the corrosion resistance and the adhesiveness of the coating film later formed with a paint composition.
• the concentration of the cation from the same is required to be not more than 0.5 weight/volume percent, preferably not more than 0.3 weight/volume percent.
• the concentration being over 0.5 weight/volume percent, the amount of the non-volatile base formed by the hydrolysis of the water-soluble salt produced from phosphoric acid and the substance (B) and/or the reaction of such water-soluble salt with the iron substrate is increased, and the pH at the surface of the iron substrate is elevated whereby the corrosion resistance and the adhesiveness of the coating film are deteriorated.
• the substance (A) being used, the same hydrolysis and/or reaction as above proceed but, since the resulting base is volatile, it is released from the reaction system into the air and therefore the concentration of the base does not become increased.
• the pH of the after treatment solution should be from 1 to 9, preferably from 3 to 8.
• the pH is lower than 3, a tendency of producing white powdery substances or rusts on the surface of the iron substrate is seen. Particularly when the pH is lower than 1, such tendency becomes more remarkable, and a seriously unfavorable influence on the corrosion resistance and the adhesiveness of the coating film appears.
• the pH is higher than 8, the remaining of an alkaline substance on the surface of the iron substrate is seen. Particularly when the pH is over 9, such remaining becomes remarkable so as to afford an unfavorable influence on the corrosion resistance and the adhesiveness of the coating film.
• the after treatment solution preferably includes a stannous compound (e.g. stannous oxide, stannous chloride, stannous sulfate) in a concentration of 0.01 to 0.1 weight/volume %.
• a stannous compound e.g. stannous oxide, stannous chloride, stannous sulfate
• the stannous compound is effective in suppressing the production of the white powdery substance on the surface of the iron substrate.
• the after treatment solution may contain any conventional rust preventive agent or oxidizing agent in an appropriate concentration which does not substantially reduce the effect of the after treatment solution as above.
• Treatment with the said treating solutions in the steps (a) and (b) may be carried out in a per se conventional procedure such as spraying or dipping, usually at a temperature of room temperature to 80°C under a pressure of 0.3 to 20 kg/cm 2 for a period of 1 to 120 minutes.
• the iron substrate may be subjected to drying without previous water rinsing.
• the drying may be effected in any per se conventional procedure such as air blowing but natural drying is industrially advantageous particularly when the iron substrate is to be treated is of a great structure.
• the pretreatment solution which has been repeatedly used and therefore contains a high concentration of iron ion, may be subjected to treatment with an ion exchange resin to eliminaate iron ion therefrom.
• aqueous solution prepared by dissolving 75 % orthophosphoric acid in water to make a concentration of 12 % of orthophosphoric acid.
• aqueous solution prepared by dissolving 75 % orthophosphoric acid and an acid pickling inhibitor "Rodin No. 57” (the polycondensate of o-toluidine and thiourea; manufactured by Nippon Paint Co., Ltd.) in water to make a concentration of 12 % of orthophosphoric acid and a concentration of 0.05 % of the acid pickling inhibitor.
• aqueous solution prepared by dissolving 75 % orthophosphoric acid and stannous chloride dihydrate in water to make a concentration of 12 % of orthophosphoric acid and a concentration of 0.05 % of stannous chloride.
• aqueous solution prepared by dissolving 75 % of orthophosphoric acid, the acid pickling inhibitor as in A-2 and stannous chloride dihydrate in water to make a concentration of 12 % of orthophosphoric acid, a concentration of 0.005 % of the acid pickling inhibitor and a concentration of 0.05 % of stannous chloride.
• aqueous solution prepared by dissolving ammonium dihydrogen phosphate and disodium hydrogen phosphate dodecahydrate in water to make a concentration of 0.432 % of ammonium dihydrogen phosphate and a concentration of 0.019 % of disodium hydrogen phosphate (pH, 5.0 to 5.5; total ion concentration, 0.44 %).
• aqueous solution prepared by dissolving ammonium dihydrogen phosphate, disodium hydrogen phosphate dodecahydrate and stannous chloride dihydrate in water to make a concentration of 0.35 % of ammonium dihydrogen phosphate, a concentration of 0.02 % of disodium hydrogen phosphate and a concentration of 0.018 % of stannous chloride (pH, 5.0 to 5.5; total ion concentration, 0.37 %).
• aqueous solution prepared by dissolving ammonium dihydrogen phosphate, disodium hydrogen phosphate dodecahydrate and sodium tripolyphosphate in water to make a concentration of 0.46 % of ammonium dihydrogen phosphate, a concentration of 0.02 % of disodium hydrogen phosphate and a concentration of 0.02 % of sodium tripolyphosphate (pH, 5.3 to 5.8; total ion concentration, 0.49 %).
• aqueous solution prepared by dissolving sodium phosphate and sodium nitrite in water to make a concentration of 2.3 % of sodium phosphate and a concentration of 1.7 %.
• aqueous solution prepared by dissolving dicyclohexylamine oleate in water to make a concentration of 4 % of dicyclohexylamine oleate.
• test pieces shot-blasted hot-rolled steel plate
• Table 1 The test pieces (shot-blasted hot-rolled steel plate) were left in the open air for ten days and then subjected to chemical treatment as shown in Table 1.
• test pieces were subjected to observation regarding rust formation and white powder formation.
• the results of the observations were indicated by the following marks: no rusting, o; less than 10 % rusting, o; 10 to 50 % rusting, ⁇ ; more than 50 % rusting, x.
• the adhesiveness was examined by the aid of an adherogaugemeter "Tonite 504 E" (manufactured by Motofuji Co., Ltd.), and the evaluation was indicated by the following marks: higher than 40 kg/cm 2 , o; 30 to 40 kg/cm 2 , o; 20 to 30 (but not 30) kg/cm 2 , ⁇ ; lower than 20 kg/cm 2 , x.
• Tonite 504 E manufactured by Motofuji Co., Ltd.
• the evaluation of the corrosion resistance was made on the test pieces after immersing in 5 % aqueous sodium chloride solution at 40°C for 60 days.
• the ASTM blister standard was adopted and the following marks were used: less than 6M, o; 6M to 4MD (but not 4MD), o; 4MD to 2D, ⁇ ; more than 2D, x.
• the percentage of rustings was indicated by the following marks: less than 5 %, o; 5 to 25 (but not 25) %, o; 25 to 50 %, ⁇ , more than 50 %, x.
• Example 2 Adopting the substantially same conditions as in Example 1, a test piece was treated with the pretreatment solution A-2 and then treated with the after treatment solution B-1 and B-4 contaminated with the pretreatment solution A-2. The same tar epoxy paint or inorganic zinc paint as in Example 1 was applied on the thus treated test piece.
• aqueous solution prepared by dissolving 75 % orthophosphoric acid in water to make a concentration of 12 % of orthophosphoric acid.
• aqueous solution prepared by dissolving 75 % orthophosphoric acid and the acid pickling inhibitor as in A-2 in water to make a concentration of 12 % of orthophosphoric acid and a concentration of 0.05 % of the acid pickling inhibitor.
• aqueous solution prepared by dissolving ammonium dihydrogen phosphate and disodium hydrogen phosphate dodecahydrate in water to make a concentration of 0.432 % of ammonium dihydrogen phosphate and a concentration of 0.019 % of disodium hydrogen phosphate (pH, 5.0 to 5.5; total ion concentration, 0.440 %).
• test pieces as in Example 1 were left in the open air for ten days and then subjected to chemical treatment as shown in Table 4.
• test pieces were subjected to observation regarding rust formation and white powder formation.
• the results of the observations were indicated by the marks having the same meanings as in Example 1.
• Example 2 After natural drying for 2 weeks, the adhesiveness and the corrosion resistance were examined.
• the adhesiveness was examined by the aid of an adhesion tester "Adhesion Tester Model 106" (manufactured by Elco Meter Co., Ltd.), and the evaluation was indicated by the following marks: higher than 30 kg/cm 2 , ;20 to 30 kg/cm 2 ,o; 10 to 20 (but not 20) kg/cm 2 , ⁇ ; lower than 10 kg/cm 2 , x.
• Adhesion Tester Model 106 manufactured by Elco Meter Co., Ltd.
• the evaluation of the corrosion resistance was made on the test pieces after immersing in 3 % aqueous sodium chloride solution at room temperature for 3 months while blowing air therein.
• the ASTM blister standard was adopted and the following marks were used: 8 to 6F, ; 4 to 2F, 8 to 4M,o; 2M, 8 to 2MD, ⁇ ; 8 to 4D, x; less than 2D, xx.
• the percentage of rustings was indicated by the following marks: less than 1 %, ; 1 to 5 (but not 5) %, o; 5 to 25 (but not 25) %, ⁇ ; 25 to 50 %, x.
• the pretreatment solution A-6 in Example 3 was prepared and used.
• test pieces as in Example 1 were left in the open air for ten days and then subjected to chemical treatment, i.e. pretreatment, after treatment and natural drying in order under the following conditions:
• Pretreatment temperature, 50° ⁇ 5°C; time, 30 minutes; spray pressure, 1 kg/cm 2 .
• the interval time between one step and the subsequent step 15 minutes.
• test pieces were subjected to pH measurements and the remaining salt concentration on the surface.
• the pH measurement was made by determining the pH of the water dropped on the surface with a pH test paper.
• the remaining salt concentration was determined by immersing the test piece of 10 cm ⁇ 15 cm in size into 200 ml of pure water, measuring the electro-conductivity of the immersed water and deducing the electro-conductivity value of pure water from the measured value.
• Example 3 the tar epoxy paint as in Example 1 was applied thereon to form a coating film of 100 ⁇ 10 ⁇ .
• the adhesiveness and the corrosion resistace of the coating film were examined as in Example 3.
• the corrosive resistance and the adhesiveness of the coating film are deteriorated when the pH of the after treatment solutions, irrespective of using sodium salts or ammonium salts is not within a range of 1 to 9.
• the pH is within a range of 1 to 9
• a higher concentration of sodium ion in the after treatment solution results in a higher pH and a higher concentration of the remaining salt at the surface of the test piece with the deterioration of the corrosion resistance of the coating film.
• the pH at the surface is almost constant in a slightly acidic range, irrespective of the total ion concentration and the pH of the after treatment solution, the remaining salt concentration is low and the corrosion resistance of the coating film is good.
• the pretreatment solution A-6 in Example 3 was prepared and used.
• the after treatment solutions B-10 and B-18 in Example 4 were prepared and each admixed with the said pretretment solution A-6 (and a phosphate) to make the compositions, the ion concentrations and the pH values as shown in Table 8.
• test pieces as in Example 1 were left in the open air for ten days and then subjected to chemical treatment, i.e. pretreatment, after treatment and natural drying in order under the following conditions:
• Pretreatment temperature, 50° ⁇ 5°C; time, 30 minutes; spray pressure, 1 kg/cm 2 .
• the interval time between one step and the subsequent step 15 minutes.
• test pieces were subjected to pH measurements and the remaining salt concentration on the surface as in Example 4.
• Example 3 the tar epoxy paint as in Example 1 or an oily rust preventing paint "LZ primer" (manufactured by Nippon Paint C0., Ltd.) was applied on the treated surface of the test piece to form a coating film of 60 ⁇ 5 ⁇ in thickness.
• the adhesiveness and the corrosion resistance of the coating film were examined as in Example 3.
• the test piece was immersed in an aqueous sodium chloride solution for 1.5 months, and the corrosion resistance was evaluated in the same manner as in using the tar epoxy paint.
• the after treatment solution obtained by admixing the original after treatment solution B-10 or B-18 with a designed amount of the pretreatment solution A-6 and adjusting the pH to 5-6 causes the production of rustings and the deterioration of the corrosion resistance and the adhesiveness of the coating film when the total ion concentration is less than 0.2 %.
• the total ion concentration being relatively low, i.e. 0.5 to 1.1 %, the difference depending on the kind of the phosphate used for regulation of the pH is not materially seen.
• the total ion concentration being relatively large, i.e. 1.9 to 6.2 %, a considerable difference is produced on the surface condition of the test piece and the corrosion resistance of the coating film.
• the pretreatment solution A-6 in Example 1 was prepared and used.
• the after treatment solutions B-35 to B-40 having the compositions, the total ion concentrations and the pH values as shown in Table 10 were prepared.
• the sodium ion and the ammonium ion were employed in the form of the primary phosphate salt.
• test pieces as in Example 1 were left in the open air for ten days and then subjected to chemical treatment, i.e. pretreatment, after treatment and natural drying in order under the following conditions:
• Pretreatment temperature, 50° ⁇ 5°C; time, 30 minutes; spray pressure, 1 kg/cm 2 .
• the interval time between one step and the subsequent step 15 minutes.
• Example 3 On the treated surface of the test pieces, the tar epoxy paint as in Example 1 or the oily rust preventing paint as in Example 5 was applied to make a coating film of 60 ⁇ 5 ⁇ in thickness. The adhesiveness and the corrosion resistance of the coating film were examined as in Example 3. In the case of using the oily rust preventing paint, the test pieces were immersed in an aqueous sodium chloride solution for 1.5 months, and the corrosion resistance was evaluated in the same manner as in using the tar epoxy resin paint.
• the pretreatment solution A-6 in Example 3 was prepared and used.
• aqueous solution prepared by dissolving ammonium dihydrogen phosphate, sodium pyrophosphate and sodium nitrite in water to make a concentration of 0.45 % of ammonium dihydrogen phosphate, a concentration of 0.05 % of sodium pyrophosphate and a concentration of 0.01 % of sodium nitrite (pH 6.0; total ion concentration, 0.51 %).
• test pieces as in Example 1 were left in the open air for twenty days and then subjected to chemical treatment, i.e. pretreatment, after treatment and natural drying in order under the following conditions:
• Pretreatment temperature, 50° ⁇ 5°C; time, 30 minutes; spray pressure, 1 kg/cm 2 .
• the interval time between one step and the subsequent step 15 minutes.
• Example 3 On the treated surface of the test pieces, the tar epoxy paint as in Example 1 or the oily rust preventing paint as in Example 5 was applied to make a coating film of 60 ⁇ 5 ⁇ in thickness. The adhesiveness and the corrosion resistance of the coating film were examined as in Example 3. In case of using the oily rust preventing paint, the test pieces were immersed in an aqueous sodium chloride solution for 1.5 months, and the corrosion resistance was evaluated in the same manner as in using the tar epoxy resin paint.

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• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Treatment Of Metals (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

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Citations (4)

• 1972
  • 1972-11-22 JP JP11737872A patent/JPS5425500B2/ja not_active Expired
• 1973
  • 1973-11-21 US US05/417,759 patent/US3961991A/en not_active Expired - Lifetime
  • 1973-11-22 DE DE2358147A patent/DE2358147A1/de not_active Ceased
  • 1973-11-22 GB GB5414873A patent/GB1425871A/en not_active Expired
  • 1973-11-22 SE SE7315818A patent/SE397845B/xx unknown

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